Skin is the largest organ of the human body, representing approximately 16% of a person's total body weight. Because it interfaces with the environment, skin has an important function in body defense, acting as an anatomical barrier from pathogens and other environmental substances. Skin also provides a semi-permeable barrier that prevents excessive fluid loss while ensuring that essential nutrients are not washed out of the body. Other functions of skin include insulation, temperature regulation, and sensation. Skin tissue may be subject to many forms of damage, including burns, trauma, disease, and depigmentation.
Skin grafts are often used to repair such skin damage. Skin grafting is a surgical procedure in which a section of skin is removed from one area of a person's body (autograft), removed from another human source (allograft), or removed from another animal (xenograft), and transplanted to a recipient site of a patient, such as a wound site. As with any surgical procedure, skin grafting involves certain risks. Complications may include graft failure, rejection of the skin graft, bleeding, fluid accumulation or infection at either the donor or recipient site. Additionally, when an autograft is taken from one area of a person's body to produce the graft, some degree of trauma occurs at the donor site. If the recipient site is a large wound or otherwise damaged skin region, the trauma at the donor site can be significant.
Techniques have been developed for harvesting a large number of smaller grafts, e.g., so-called micrografts, to reduce the trauma at the donor site. By removing only a fraction of the skin at a donor site and leaving regions of healthy skin surrounding the excised regions, a large amount of skin for transplantation can be obtained with less discomfort. Micrograft harvesting can also reduce the healing time and risk of infection.
Harvesting of skin grafts can be accomplished in many different ways. One common technique for harvesting a skin graft involves the application of suction to separate a surface portion of the skin, e.g., the epidermis and a basal cell layer, from the underlying dermis. Harvesting of suction blisters typically also involves a heat source to facilitate blister formation.
Various devices are available for generating and harvesting micrografts. For example, the Cellutome™ skin harvester is available from Kinetic Concepts, Inc. of San Antonio, Tex. The Cellutome™ system includes a head that provides a source of reduced pressure (vacuum), and optionally a heater element, and a harvester configured for placement on a target region of a patient's skin. The harvester is further adapted to form a sealing engagement with the head such that the target region of skin is embraced within an evacuated chamber. The Cellutome™ harvester further includes at least one alignment plate having a plurality of holes through which skin blisters can be raised in the presence of negative pressure; and a cutting plate having at least one cutting surface for cleaving skin blisters after they are formed within the chamber.
Typically, micrograft harvesters rely upon a support or substrate to lift the excised blisters from the device. The substrate is then applied to a recipient site so that the plurality of micrografts can be assimilated as transplanted tissue. Ideally, the grafts will expand and coalesce to complete the healing process.